Consider more carefully your ranking of preferences, and expand your horizons quite a bit. There're lots of ways to improve the predicted future state of humanity that are less direct, but possibly more effective, than this particular topic.

I care about the current and future state of humanity

That's sweet of you. I'm glad.

so I think it's good to work on existential or global catastrophic risk

That's a pretty big jump. I'll grant that human existential risk is important, but why is your best contribution to work directly on it? Perhaps you'd do a lot more good with a slight reduction in shipping costs or tiny improvements in safety or enjoyment of some consumer product. In the likely case that your marginal contribution to x-risk doesn't save the world, a small improvement for a large number of people does massive amounts more good.

Regardless of whether you focus on x-risk or something else valuable, the fact that you won't consider leaving Kagoshima is an indication that you aren't as fully committed as you claim. IMO, that's ok: we all have personal desires that we put ahead of the rest of the world. But you should acknowledge it and include it in your calculations.